Dak, as shown in the NRC measurements here , the M22 impedance drops to about 3 ohms in the upper mid-range/lower treble, but this is certainly no cause for worry and hasn't given me any for the past 9 years. The heat load on an amplifier isn't determined by the lowest speaker impedance in a particular frequency range, but by the average impedance over the entire frequency range when playing music.

-----------------------------------

Enjoy the music, not the equipment.